The　adsorption　energy　of　the　4C1Si　island　configurations　and　the　diffusion　activation　energies　of　carbon　and　silicon　atoms　on　diamond　(001)　surface　were　calculated　with　first　principle　method　based　on　density　functional　theory　(DFT)　to　study　the　growth　of　diamond　films　and　the　growth　position　of　silicon　particles　after　they　are　mixed　into　the　composite　film.　The　4C1Si　island　configurations　consist　of　five　types　of　C-by-3C1Si　configurations　and　four　types　of　Si-by-4C　configurations.　The　adsorption　energy　and　total　energy　of　the　4C1Si　island　configurations　were　calculated　firstly.　In　addition,　the　diffusion　activation　energies　of　the　carbon　and　silicon　atoms　were　calculated.　The　results　show　that:　(1)　the　adsorption　energy　of　the　Si-by-4C　island　configurations　is　higher　than　that　of　the　C-by-3C1Si　island　configurations.　This　indicates　that　it　is　not　easy　for　silicon　atoms　to　remain　stable　in　the　3C1Si　island.　In　contrast,　silicon　atoms　are　easy　to　move　out　of　the　island　so　that　the　carbon　atoms　out　of　the　3C1Si　Island　can　enter　the　island　to　form　the　4C　island;　(2)　Compared　with　the　carbon　atom,　silicon　atom　needs　lower　diffusion　activation　energy　to　move　into　or　out　of　the　island.　This　shows　that　silicon　atoms　are　more　active　than　carbon　atoms.　Thus,　it　is　easier　for　silicon　particles　to　fill　the　vacancy　defects　in　diamond/Si　films,　improving　the　compactness　of　the　diamond　composite　films.　(C)　2014　Elsevier　B.V.　All　rights　reserved.